From 8047310ee984b3efe932ee5b561f2523396466dd Mon Sep 17 00:00:00 2001 From: Guennadi Liakhovetski Date: Wed, 12 Dec 2012 15:38:14 +0100 Subject: [PATCH] mmc: sh_mmcif: fix a race, causing an Oops on SMP Oopses have been observed on SMP in the sh-mmcif IRQ thread, when the two IRQ threads run simultaneously on two CPUs. Also take care to guard the timeout work and the DMA completion callback from possible NULL-pointer dereferences and races. Signed-off-by: Guennadi Liakhovetski Signed-off-by: Chris Ball --- drivers/mmc/host/sh_mmcif.c | 39 ++++++++++++++++++++++++++++++++++++--- 1 file changed, 36 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c index de4b6d0..3cfe383 100644 --- a/drivers/mmc/host/sh_mmcif.c +++ b/drivers/mmc/host/sh_mmcif.c @@ -56,6 +56,7 @@ #include #include #include +#include #include #include #include @@ -196,6 +197,7 @@ enum mmcif_state { STATE_IDLE, STATE_REQUEST, STATE_IOS, + STATE_TIMEOUT, }; enum mmcif_wait_for { @@ -232,6 +234,7 @@ struct sh_mmcif_host { int sg_blkidx; bool power; bool card_present; + struct mutex thread_lock; /* DMA support */ struct dma_chan *chan_rx; @@ -255,11 +258,11 @@ static inline void sh_mmcif_bitclr(struct sh_mmcif_host *host, static void mmcif_dma_complete(void *arg) { struct sh_mmcif_host *host = arg; - struct mmc_data *data = host->mrq->data; + struct mmc_request *mrq = host->mrq; dev_dbg(&host->pd->dev, "Command completed\n"); - if (WARN(!data, "%s: NULL data in DMA completion!\n", + if (WARN(!mrq || !mrq->data, "%s: NULL data in DMA completion!\n", dev_name(&host->pd->dev))) return; @@ -1113,11 +1116,21 @@ static bool sh_mmcif_end_cmd(struct sh_mmcif_host *host) static irqreturn_t sh_mmcif_irqt(int irq, void *dev_id) { struct sh_mmcif_host *host = dev_id; - struct mmc_request *mrq = host->mrq; + struct mmc_request *mrq; bool wait = false; cancel_delayed_work_sync(&host->timeout_work); + mutex_lock(&host->thread_lock); + + mrq = host->mrq; + if (!mrq) { + dev_dbg(&host->pd->dev, "IRQ thread state %u, wait %u: NULL mrq!\n", + host->state, host->wait_for); + mutex_unlock(&host->thread_lock); + return IRQ_HANDLED; + } + /* * All handlers return true, if processing continues, and false, if the * request has to be completed - successfully or not @@ -1125,6 +1138,7 @@ static irqreturn_t sh_mmcif_irqt(int irq, void *dev_id) switch (host->wait_for) { case MMCIF_WAIT_FOR_REQUEST: /* We're too late, the timeout has already kicked in */ + mutex_unlock(&host->thread_lock); return IRQ_HANDLED; case MMCIF_WAIT_FOR_CMD: /* Wait for data? */ @@ -1166,6 +1180,7 @@ static irqreturn_t sh_mmcif_irqt(int irq, void *dev_id) if (wait) { schedule_delayed_work(&host->timeout_work, host->timeout); /* Wait for more data */ + mutex_unlock(&host->thread_lock); return IRQ_HANDLED; } @@ -1179,6 +1194,7 @@ static irqreturn_t sh_mmcif_irqt(int irq, void *dev_id) sh_mmcif_stop_cmd(host, mrq); if (!mrq->stop->error) { schedule_delayed_work(&host->timeout_work, host->timeout); + mutex_unlock(&host->thread_lock); return IRQ_HANDLED; } } @@ -1189,6 +1205,8 @@ static irqreturn_t sh_mmcif_irqt(int irq, void *dev_id) host->mrq = NULL; mmc_request_done(host->mmc, mrq); + mutex_unlock(&host->thread_lock); + return IRQ_HANDLED; } @@ -1262,11 +1280,24 @@ static void mmcif_timeout_work(struct work_struct *work) struct delayed_work *d = container_of(work, struct delayed_work, work); struct sh_mmcif_host *host = container_of(d, struct sh_mmcif_host, timeout_work); struct mmc_request *mrq = host->mrq; + unsigned long flags; if (host->dying) /* Don't run after mmc_remove_host() */ return; + dev_dbg(&host->pd->dev, "Timeout waiting for %u, opcode %u\n", + host->wait_for, mrq->cmd->opcode); + + spin_lock_irqsave(&host->lock, flags); + if (host->state == STATE_IDLE) { + spin_unlock_irqrestore(&host->lock, flags); + return; + } + + host->state = STATE_TIMEOUT; + spin_unlock_irqrestore(&host->lock, flags); + /* * Handle races with cancel_delayed_work(), unless * cancel_delayed_work_sync() is used @@ -1410,6 +1441,8 @@ static int sh_mmcif_probe(struct platform_device *pdev) goto erqcd; } + mutex_init(&host->thread_lock); + clk_disable(host->hclk); ret = mmc_add_host(mmc); if (ret < 0) -- 2.7.4